Cat 420eit Stabilizer wont go down

[justsomedude]

Hello all. Hoping for a bit of guidance here as im no expert

I have a Cat 420eit (SN: DAN00662) one of the stabilizer legs wont go down. It is currently up all the way. i have noticed some things that lead me to believe it is something to do with the valve in the valve bank at the rear of the machine.
Observations:
1. the lines from the valve bank to the non working cylinder get warm from just idling the tractor. the lines to the working stabilizer are cold. Pilot lines going to the valve also stay cold

2. there is a sound that sounds like flow is happening without the control being touched.

3. moving the control to put the leg down produces no sound or movement.

3 moving the control to pull the leg up produces sound like the pump is working but no movement (leg is all the way up).

4. i swapped the pilot lines going to the valve bank to see if any changes would happen.
the sounds listed in observation 3 swapped to the other control direction but no movement on the cylinder.

Any idea what i might be looking at or suggestions to look at / try ?

 

[highwayghost]

Could the cylinder rod have gotten bent and the cylinder is stuck? If you loosen the fittings on the cylinder the cylinder should move.

 

[Vetech63]

You could just loosen the lines on your cylinder at both ends, then start it up. If you have pressure with the control in neutral, you have a valve issue (could be pilot or main valve). By your description above, it sounds like you have pressure to one end of the cylinder constantly.

 

[justsomedude]

It ended up being a badly bent rod. Took it to a shop to see if they could just replace the rod but the cylinder wall is messed up the piston is damage the gland is damaged so i just ended up getting a completely new one. Problem now is the thing drifts down on its own. Cat said the poppets in the valve are worn out. Has anyone had experience replacing a poppet kit in the valve? Cat wants to charge 10 hours to do this. I cant find any instructions anywhere however from the parts diagram it does not look like a big deal. Any one have some experience to share? Is it worth having them do or its simple enough for a non expert?

 

[Vetech63]

It ended up being a badly bent rod. Took it to a shop to see if they could just replace the rod but the cylinder wall is messed up the piston is damage the gland is damaged so i just ended up getting a completely new one. Problem now is the thing drifts down on its own. Cat said the poppets in the valve are worn out. Has anyone had experience replacing a poppet kit in the valve? Cat wants to charge 10 hours to do this. I cant find any instructions anywhere however from the parts diagram it does not look like a big deal. Any one have some experience to share? Is it worth having them do or its simple enough for a non expert?

If you are talking about the hold valve just replace it as a unit. I have never had success screwing around with them trying to get them to work properly. You could take it apart just see see if it has a piece of metal stuck in it though......it could be that simple.

 

[justsomedude]

well i took it apart and there were chunks of metal from presumably from the old cylinder in it. removed the debris and replaced the poppet kits in both sides the the valve. the old ones were clearly bad. hooked everything back up and the cylinder still drifts down just a bit more slowly now. could there be some problem with the spool or some kind of debris in the spool that would cause this? New cylinder new check valves none of the other cylinders drift at all. Anybody have any suggestions or ideas to troubleshoot or diagnose this?

 

[Vetech63]

well i took it apart and there were chunks of metal from presumably from the old cylinder in it. removed the debris and replaced the poppet kits in both sides the the valve. the old ones were clearly bad. hooked everything back up and the cylinder still drifts down just a bit more slowly now. could there be some problem with the spool or some kind of debris in the spool that would cause this? New cylinder new check valves none of the other cylinders drift at all. Anybody have any suggestions or ideas to troubleshoot or diagnose this?

Thats why I said to replaced the valve assembly as a unit. One scratch in the poppet seat or spool that you can hang your fingernail on and it will still leak. If you replace the valve and it still drifts, then you have leakage inside the cylinder itself.

 

[justsomedude]

We eliminated the cylinder being the issue by putting the stabilizer down with some pressure on it, turning off the machine and cracking the hose connection to the side of the cylinder responsible for retracting the stabilizer. stabilizer didnt move and no substantial leakage from where we disconnected the hose so the packing the in cylinder wasn't allowing any oil to bypass it. It turned out to be some kind of problem with the relief valve on the section of the valve bank that controls that cylinder. I did not to this test myself but aparently they swapped the relief valve which had no signs of external leakage for a plug and that stopped the drift so we replaced the relief valve and now the issue is solved.

A big thank you to everyone who made suggestions and shared their experience knowledge and expertise with this. I really appreciate you all taking time out of your day to help a random guy on the internet.